Controller of internal combustion engine

ABSTRACT

Tooth portions are formed at unit angles on a rotor connected with a crankshaft of an internal combustion engine. A toothless portion is formed on the rotor by irregularly changing the regular arrangement of the tooth portions. A controller of the engine estimates times necessary for rotation of unit angles of an arbitrary angular range of 50° CA including the toothless portion and a pair of tooth portions adjacent to the toothless portion by using times necessary for rotation of unit angles of a different angular range of 50° CA distant from the arbitrary angular range by 180° CA. Thus, the controller can maintain high controllability of the engine even when there occurs a range where the time necessary for the rotation of the crankshaft is not sensed appropriately.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese Patent Application No. 2006-131411 filed on May 10, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a controller of an internal combustionengine having a function of sensing a time necessary for a unit angle ofa crankshaft of the engine to rotate based on an output of a crank anglesensor sensing sensed portions formed for respective unit angles atequal intervals on a rotating body rotating in synchronization withrotation of the crankshaft.

2. Description of Related Art

It is common knowledge to sense multiple tooth portions (sensedportions) formed at equal intervals on a rotor provided on a crankshaftof an in-vehicle internal combustion engine with a crank angle sensor inorder to calculate a time necessary for the crankshaft to rotate. Amagnetic flux between the crank angle sensor and the rotor changesregularly because a positional relationship between the crank anglesensor, which is located near the rotor, and the tooth portions of therotor changes regularly. Paying attention to this fact, the rotation ofthe tooth portions of the rotor is sensed based on the regular fluxchange.

In order to sense a reference position of the rotation angle of thecrankshaft, a toothless portion is usually provided on the rotor byirregularly changing the disposal of the above-described tooth portions.Accordingly, the regularity of the flux change is disturbed if the crankangle sensor approaches to the toothless portion while the magnetic fluxbetween the crank angle sensor and the rotor changes regularly with therotation of the crankshaft. The reference position of the rotation angleof the crankshaft can be sensed based on disturbance of the regularityof the flux change.

However, since the regularity of the flux change is disturbed near thetoothless portion, the rotation angle cannot be sensed with highaccuracy. Control based on information with high accuracy about therotation angle of the crankshaft cannot be performed if the engine iscontrolled based on the sensing value of the crank angle sensor. As aresult, controllability deteriorates and there is a possibility thatexhaust characteristics and drivability are deteriorated. For example,JP-A-2005-48644 describes a controller that controls an internalcombustion engine based on a rotation angle of a crankshaft.

The problem of the deterioration of the controllability of the engine isnot limited to the angle range having the toothless portion. Thisproblem is common to a range where the time necessary for the rotationcannot be sensed appropriately, such as, a range where the timenecessary for the rotation of the crankshaft cannot be sensedtemporarily.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a controller of aninternal combustion engine capable of maintaining high controllabilityof the engine even when there occurs a range where a time necessary forrotation of a crankshaft cannot be sensed appropriately.

According to an aspect of the present invention, a controller of aninternal combustion engine has a first necessary time sensing devicethat senses a first necessary time necessary for rotation of anarbitrary angular range of the crankshaft, a second necessary timesensing device that senses a second necessary time necessary forrotation of an angular range different from the arbitrary angular range,a unit necessary time sensing device that senses multiple unit necessarytimes necessary for rotation of unit angles in the angular rangedifferent from the arbitrary angular range, and an estimating devicethat estimates times necessary for rotation of unit angles in thearbitrary angular range by converting the multiple unit necessary timesinto equivalents of the times necessary for the rotation of the unitangles in the arbitrary angular range based on a difference between thefirst necessary time and the second necessary time.

A tendency of rotation fluctuation in the arbitrary angular range iscorrelated with the unit necessary times necessary for the rotation ofthe unit angles of the different angular range. The times necessary forthe rotation of the unit angles in the arbitrary angular range candiffer from the times necessary for the rotation of the unit angles ofthe different angular range. The difference corresponds to thedifference between the first necessary time necessary for the rotationof the arbitrary angular range and the second necessary time necessaryfor the rotation of the difference angular range.

Therefore, regarding the rotation fluctuation in the arbitrary angularrange grasped with the unit necessary times, the above-describedstructure grasps the magnitude of the times necessary for the rotationof the unit angles in the arbitrary angular range based on thedifference between the first necessary time and the second necessarytime. That is, the unit necessary times are converted into theequivalents of times necessary for the rotation of the unit angles inthe first necessary time based on the difference between the firstnecessary time and the second necessary time. Thus, the converted valuesare estimated as the times necessary for the rotation of the unit anglesin the arbitrary angular range.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments will be appreciated, as well asmethods of operation and the function of the related parts, from alearning of the following detailed description, the appended claims, andthe drawings, all of which form a part of this application. In thedrawings:

FIG. 1 is a schematic diagram showing an entire structure of an enginesystem according to a first embodiment of the present invention;

FIGS. 2A and 2B are enlarged views showing a rotor and a crank anglesensor according to the first embodiment;

FIGS. 3A and 3B are time charts showing transitions of rotation speed ofcylinders according to the first embodiment;

FIG. 4 is a block diagram showing control blocks for calculating an eachcylinder work amount according to the first embodiment;

FIG. 5 is a time chart showing transitions of the rotation speed, aninstantaneous torque equivalent, and the each cylinder work amountaccording to the first embodiment;.

FIG. 6 is a flowchart showing processing steps for learning a learningvalue according to the first embodiment;

FIG. 7 is a time chart for explaining problems regarding sensing of atime necessary for a unit angle to rotate according to the firstembodiment;

FIG. 8 is a flowchart showing processing steps for estimating the timenecessary for the unit angle to rotate according to the firstembodiment;

FIG. 9 is a time chart showing a processing mode according to the firstembodiment;

FIG. 10 is a flowchart showing processing steps for estimating a timenecessary for a unit angle to rotate according to a second embodiment ofthe present invention; and

FIG. 11 is a time chart showing a processing mode according to thesecond embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

A controller of an internal combustion engine according to a firstembodiment of the present invention is applied to a fuel injectioncontroller of a diesel engine. FIG. 1 shows an entire structure of anengine system according to the present embodiment. As shown in FIG. 1, afuel pump 6 suctions fuel from a fuel tank 2 through a fuel filter 4.The fuel pump 6 receives a driving force from a crankshaft 8 (i.e., anoutput shaft of the engine) and discharges the fuel. The fuel pump 6 hasa suction metering valve 10. The suction metering valve 10 regulates anamount of the fuel discharged from the fuel pump 6 by regulating anamount of the suctioned fuel. That is, the amount of the fuel dischargedto an outside is decided by the operation of the suction metering valve10. The fuel pump 6 has multiple plungers, each of which reciprocatesbetween a top dead center and a bottom dead center to suction and todischarge the fuel.

The fuel discharged from the fuel pump 6 is supplied under pressure(i.e., pressure-fed) to a common rail 12. The common rail 12 stores thefuel pressure-fed from the fuel pump 6 at a high-pressure state andsupplies the fuel to injectors 16 of respective cylinders (fourcylinders are illustrated in FIG. 1) through high-pressure fuel passages14. The injectors 16 are connected with the fuel tank 2 through alow-pressure fuel passage 18.

The engine system according to the present embodiment has varioussensors for sensing operation states of the engine such as a fuelpressure sensor 20 for sensing the fuel pressure in the common rail 12and a crank angle sensor 22 for sensing a rotation angle of thecrankshaft 8 based on rotation of a rotor 9 provided on the crankshaft8. The engine system has an accelerator sensor 24 for sensing anoperation amount ACCP of an accelerator pedal operated in response toacceleration demand of a user.

An electronic control unit 30 (ECU) includes a microcomputer as a maincomponent. The ECU 30 takes in the sensing results of the varioussensors and controls an output of the engine based on the sensingresults. The ECU 30 performs fuel injection control in order to performthe output control appropriately.

The rotation angle of the crankshaft 8 is sensed by the crank anglesensor 22 in a manner shown in FIGS. 2A and 2B. Convex tooth portions 9a as sensed portions are formed on the rotor 9, which rotates integrallywith the crankshaft 8, at equal intervals (10° CA in this example). Atoothless portion 9 b is formed on the rotor 9 by irregularly changingthe regular disposal of the tooth portions 9 a. In the presentembodiment, the toothless portion 9 b is formed as a convex memberhaving width (30° CA in this example) greater than that of the toothportion 9 a.

The crank angle sensor 22 is a sensor of an electromagnetic inductiontype located near the tooth portions 9 a of the rotor 9. A magnetic fluxintersecting a coil 22 a of the crank angle sensor 22 increases anddecreases because the disposal mode between the shape of the rotor 9with the convexes and concaves and the crank angle sensor 22 changes ifthe rotor 9 rotates. Voltage proportional to the rotation speed isoutputted from the crank angle sensor 22 as a sensing signal due toelectromagnetic induction caused by the change in the magnetic flux.

The rotation speed of the crankshaft 8 is controlled as desired throughthe above-described fuel injection control. If this rotation speed isanalyzed in minute time intervals, it is shown that increase anddecrease of the rotation speed are repeated in synchronization withrespective strokes in a combustion cycle. As shown in FIG. 3A, thecombustion is performed in the first cylinder #1, the third cylinder #3,the fourth cylinder #4, and the second cylinder #2 in that order. InFIG. 3A, #1-#4 represent combustion timings of the first to fourthcylinders #1-#4 respectively. The fuel is injected every 180° CA and iscombusted. During the combustion cycle (180° CA) of each cylinder, arotating force is applied to the crankshaft 8 along with the combustionsuch that the rotation speed increases, and then, the rotation speeddecreases because of loads applied to the crankshaft 8 and the like. Inthis case, it is expected that a work amount for each cylinder can beestimated in accordance with the behavior of the rotation speed.

It is expected that the work amount of each cylinder can be calculatedfrom the rotation speed at the end timing of the combustion cycle of thecylinder. For example, as shown in FIG. 3B, the work amount of the firstcylinder #1 is calculated at timing t1 as the end timing of thecombustion cycle of first cylinder #1. The work amount of the followingthird cylinder #3 is calculated at timing t2 as the end timing of thecombustion cycle of the third cylinder #3. However, in this case, therotation speed calculated from the unit angles of the crankshaft 8,which are grasped through the output (NE pulses) of the crank anglesensor 22, includes noises or components caused by a sensing error. Asshown in FIG. 3B, the sensed value (solid line b in FIG. 3B) of therotation speed varies with respect to the actual rotation speed (brokenline a in FIG. 3B). Therefore, an exact work amount cannot be calculatedat timings t1, t2 and the like. In FIG. 3B, a chain double-dashed line cshows a transition of the calculated work amounts of the cylinders.

Therefore, in the present embodiment, as shown in FIG. 4, the rotationspeed Ne is inputted into a filtering section M1 as an input signal in aconstant angular cycle. The filtering section M1 calculates aninstantaneous torque equivalent Neflt by extracting only a rotationfluctuation component at each timing. The rotation speed Ne is sampledin an output cycle of the NE pulse (10° CA, in the present embodiment).For example, the filtering section Ml is provided by a BPF (band-passfilter). The BPF removes high-frequency components and low-frequencycomponents contained in the rotation speed signal. The instantaneoustorque equivalent Neflt(i) as the output of the filtering section M1 isexpressed by following Expression (1), for example.Neflt(i)=k1×Ne(i)+k2×Ne(i−2)+k3×Neflt(i−1)+k4×Neflt(i−2)  Expression(1):

In Expression (1), Ne(i) represents the present sampling value of therotation speed, Ne(i−2) is the second last sampling value of therotation speed, Neflt(i−1) is the last value of the instantaneous torqueequivalent, and Neflt(i−2) is the second last value of the instantaneoustorque equivalent. k1-k4 are constants. The instantaneous torqueequivalent Neflt(i) is calculated by Expression (1) each time therotation speed signal is inputted into the filtering section M1.

Expression (1) is obtained by discretizing a transfer function G(s)shown by following Expression (2). In Expression (2), ζ represents adamping coefficient and ω is a response frequency.

$\begin{matrix}{\mspace{20mu}\begin{matrix}{{G(s)} = \frac{2{\varsigma\omega}\; s}{s^{2} + {2{\varsigma\omega}\; s} + \omega^{2}}} & \;\end{matrix}} & {{Expression}\mspace{14mu}(2)}\end{matrix}$

Specifically, in the present embodiment, a combustion frequency of theengine is used as the response frequency ω and, in Expression (1),constants k1-k4 are set based on the setting that the response frequencyω is the combustion frequency. The combustion frequency is an angularfrequency representing the combustion frequency per unit angle. In thecase of the four cylinders, the combustion cycle (combustion angularcycle) is 180° CA. The combustion frequency is decided by the inverse ofthe combustion cycle.

An integration section M2 shown in FIG. 4 takes in the instantaneoustorque equivalent Neflt and carries out integration of the instantaneoustorque equivalent Neflt over a constant interval for each combustioncycle of each cylinder. Thus, the integration section M2 calculates thework amounts Sneflt#1-Sneflt#4 corresponding to the respective cylinders#1-#4 as the torque integration values of the respective cylinders#1-#4. NE pulse numbers 0-71 are assigned to the NE pulses outputted inthe cycle of 10° CA, respectively. The NE pulse numbers 0-17 areassigned to the combustion cycle of the first cylinder #1. The NE pulsenumbers 18-35 are assigned to the combustion cycle of the third cylinder#3. The NE pulse numbers 36-53 are assigned to the combustion cycle ofthe fourth cylinder #4. The NE pulse numbers 54-71 are assigned to thecombustion cycle of the second cylinder #2. The work amountsSneflt#1-Sneflt#4 corresponding to the cylinders #1-#4 are calculated byfollowing Expression (3) for the first to fourth cylinders #1-#4respectively.Snelft#1=Nelft(0)+Nelft(1)+ . . . +Nelft(16)+Nelft(17),Snelft#2=Nelft(18)+Nelft(19)+ . . . +Nelft(34)+Nelft(35),Snelft#3=Nelft(36)+Nelft(37)+ . . . +Nelft(46)+Nelft(47),Snelft#4=Nelft(48)+Nelft(49)+ . . . +Nelft(70)+Nelft(71)  Expression(3):

The cylinder number will be expressed as #i, and each of the workamounts Sneflt#1-Sneflt#4 corresponding to the cylinder #i will beexpressed as an each cylinder work amount Sneflt#i.

FIG. 5 is a time chart showing transitions of the rotation speed Ne, theinstantaneous torque equivalent Neflt, and the each cylinder work amountSneflt#i. As shown in FIG. 5, the instantaneous torque equivalent Nefltoscillates with respect to a reference level Ref. The each cylinder workamount Sneflt#i is calculated by integrating the instantaneous torqueequivalent Neflt within the combustion cycle of each cylinder #i. Theintegration value of the instantaneous torque equivalent Neflt on apositive side of the reference level Ref corresponds to combustiontorque, and the integration value of the instantaneous torque equivalentNeflt on a negative side of the reference level Ref corresponds to loadtorque. The reference level Ref is decided in accordance with averagerotation speed of the entire cylinders.

Essentially, the balance between the combustion torque and the loadtorque should be zero and the each cylinder work amount Sneflt#i shouldbe zero (combustion torque−load torque=0) in the combustion cycle ofeach cylinder #i. However, the each cylinder work amount Sneflt#i willvary if injection characteristics, friction characteristics or the likeof the injectors 16 differ among the cylinders because of individualdifferences among the cylinders, aging deterioration or the like. Forexample, as shown in FIG. 5, the variation is caused such that the eachcylinder work amount Sneflt#1 of the first cylinder #1 is greater thanzero and the each cylinder work amount Sneflt#2 of the second cylinder#2 is less than zero.

The differences generated between the injection characteristics of theinjector 16 or the like and ideal values in each cylinder or a degree ofthe variation in the injection characteristics among the cylinders canbe grasped by calculating the each cylinder work amounts Sneflt#i.Therefore, in the present embodiment, the deviation amounts of theinjection characteristics of the injectors 16 among the cylinders arelearned as the deviation amounts of the each cylinder work amountsSneflt#i among the cylinders by using the each cylinder work amountsSneflt#i. The processing steps of the calculation of the deviationamounts are shown in FIG. 6. The ECU 30 performs the processing when theNE pulse rises.

In FIG. 6, first, Step S10 calculates the time interval of NE pulsesfrom the present NE interruption timing and previous NE interruptiontiming. Step S1 calculates the present rotation speed Ne (instantaneousrotation speed) through inverse calculation of the time interval.Following Step S12 calculates the instantaneous torque equivalentNeflt(i) by using above-described Expression (1).

Following Step S14 determines the present NE pulse number. Steps S16-S22calculate the each cylinder work amounts Sneflt#i of the first to fourthcylinders #1-#4. If the NE pulse number is in the range of “0-17”, theeach cylinder work amount Sneflt#1 of the first cylinder #1 iscalculated at Step S16. If the NE pulse number is in the rage of“18-35”, the each cylinder work amount Sneflt#3 of the third cylinder #3is calculated at Step S18. If the NE pulse number is in the range of“36-53”, the each cylinder work amount Sneflt#4 of the fourth cylinder#4 is calculated at Step S20. If the NE pulse number is in the range of“54-71”, the each cylinder work amount Sneflt#2 of the second cylinder#2 is calculated at Step S22.

Then, Step S24 determines whether a learning condition is established.The learning condition includes a condition that the calculation of theeach cylinder work amounts Sneflt#i of the entire cylinders #i iscompleted, a condition that a power transmission device (drive train) ofa vehicle is in a predetermined state, a condition that environmentalconditions are in predetermined states, and the like. The learningcondition is determined to be established when all of the subordinateconditions are satisfied. For example, a condition that a crutch deviceof a drive train system is not in a half-crutched state may be used asthe condition related to the drive train. A condition that enginecoolant temperature is equal to or higher than predetermined warm-upcompletion temperature may be used as the environmental condition.

If the learning condition is not satisfied, the processing is endedimmediately. If the learning condition is satisfied, the process goes toStep S26. Step S26 increments a counter nitgr by one and calculatesintegration values Qlp#i for the respective cylinders #1-#4 by usingfollowing Expression (4). The integration value Qlp#i is an integrationvalue of the injection characteristic value calculated by multiplyingthe each cylinder work amount Sneflt#i by a conversion coefficient Ka.The integration value Qlp#i is for calculating the injectioncharacteristic value by performing the averaging processingpredetermined times when the counter nitgr reaches the predeterminedtimes.Qlp#i=Qlp#i+Ka×Sneflt#i  Expression (4):

The each cylinder work amounts Sneflt#i are cleared to zero if theabove-described processing is performed. Then, Step S28 determineswhether the counter nitgr reaches predetermined times kitgr. A value ofthe times kitgr is set at a value capable of inhibiting a calculationerror due to a noise and the like during the calculation of theinjection characteristic value, which is calculated by multiplying theeach cylinder work amount Snefit#i by the conversion coefficient Ka. Ifnitgr≧kitgr, the process goes to Step S30. Step S30 calculates theinjection characteristic value Qlrn#i of each cylinder by followingExpression (5). The integration value Qlp#i is cleared to zero and thecounter nitgr is also cleared to zero.Qlrn#i=Qlrn#i+Kb×Qlp#i/kitgr  Expression (5):

In Expression (5), the integration value Qlp#i integrated thepredetermined times kitgr is averaged, and the injection characteristicvalue Qlrn#i is updated with the averaged learning value. At this time,an error in the each cylinder work amount Sneflt#i at each time isabsorbed by averaging the integration value Qlp#i. In addition, inExpression (5), the coefficient Kb may be set in a range greater thanzero and not greater than one (0<Kb≦1), for example.

Then, Step S32 calculates the learning value ΔQlrn#i by followingExpression (6),

$\begin{matrix}{\mspace{20mu}\begin{matrix}{{\Delta\;{Qlrn}\# i} = {{{Qlrn}\# i} - {\frac{1}{4}{\sum{{Qlrn}\# i}}}}} & \;\end{matrix}} & {{Expression}\mspace{14mu}(6)}\end{matrix}$

The deviation amount of the injection characteristic value Qlrn#i ofeach cylinder from the average value (ΣQlrn#i/4) of the injectioncharacteristic values Qlrn#i of all the cylinders can be calculated byExpression (6).

Following Step S34 writes the learning value ΔQlrn#i in a predeterminedarea of a constantly memory-holding device. The constantlymemory-holding device is a storage device that holds data irrespectiveof ON/OFF of a main power source of the ECU 30. For example, theconstantly memory-holding device is a nonvolatile memory such as EEPROMthat holds the data irrespective of existence or nonexistence of powersupply or a backup memory that maintains an energized state irrespectiveof a state of an ignition switch.

Through the series of above-described processing, the variation in theinjection characteristics of the injectors 16 can be learned.

As shown in FIGS. 2A and 2B, the rotor 9 is formed with the toothlessportion 9 b. Accordingly, the necessary time and the speed of therotation of the unit angle (10° CA) cannot be sensed with the use of theoutput of the crank angle sensor 22 at the toothless portion 9 b.Furthermore, because of the toothless portion 9 b, regularity of themagnetic flux intersecting the coil 22 a of the crank angle sensor 22immediately after the tooth portion 9 a adjacent to the toothlessportion 9 b most approaches to the crank angle sensor 22 is disorderedunlike the magnetic flux in the portion where the tooth portions 9 a arearranged regularly at the equal intervals. FIG. 7 shows a sensing resultnear the toothless portion 9 b based on the output of the crank anglesensor 22.

Part (a) of FIG. 7 shows the number of the tooth portion 9 a (ortoothless portion 9 b) of the rotor 9 closest to the crank angle sensor22. Part (b) of FIG. 7 shows the output waveform of the crank anglesensor 22. Part (c) of FIG. 7 shows a pulse (waveform-shaped pulse)produced through waveform shaping of the output of the crank anglesensor 22. As shown in FIG. 7, the value of the output of the crankangle sensor 22 fluctuates in accordance with whether the tooth portion9 a approaches to the crank angle sensor 22 or a portion between thetooth portions 9 a approaches to the crank angle sensor 22. Thewaveform-shaped pulse generated by carrying out the waveform shaping ofthe output signal of the crank angle sensor 22 is generated as a signallogically inverting at a point, at which the output of the crank anglesensor 22 crosses zero (i.e., at zero-cross point). In detail, thewaveform-shaped pulse is a signal that rises at a point where the outputof the crank angle sensor 22 crosses zero while decreasing and thatfalls at a point where the output of the crank angle sensor 22 crosseszero while increasing. Thus, the point where the center of the crankangle sensor 22 most approaches to the tooth portion 9 a can beconformed to the rising edge of the waveform-shaped pulse. Accordingly,the angle between the rising edges of the waveform-shaped pulses can besensed as 10° CA.

Since the thirty-second tooth portion 9 a is adjacent to the toothlessportion 9 b, the next interval of 10° CA from the center of thethirty-second tooth portion 9 a cannot be sensed accurately (range B inFIG. 7). Although the interval between the thirty-second tooth portion 9a and the toothless portion 9 b is equal to the interval between thetooth portions 9 a, the magnetic flux change is small while the crankangle sensor 22 is close to the toothless portion 9 b. Accordingly, thezero-cross point delays with respect to the actual 10° CA interval.Moreover, since the first tooth portion 9 a is also adjacent to thetoothless portion 9 b, the 10° CA interval to the center of the firsttooth portion 9 a cannot be accurately sensed (range D in FIG. 7).Although the interval between the toothless portion 9 b and the firsttooth portion 9 a is equal to the interval between the tooth portions 9a, the zero-cross point delays with respect to the actual 10° CAinterval since the magnetic flux change is small while the crank anglesensor 22 is close to the toothless portion 9 b. As explained above,accurate sensing of the necessary time is impossible in range C in FIG.7 due to the toothless portion 9 b. In ranges A, E, accurate sensing ofthe necessary time is possible.

Thus, the accurate interval of 10° CA cannot be sensed based on therising edges of the waveform-shaped pulses in the interval of 50° CAfrom the center of the thirty-second tooth portion 9 a to the center ofthe first tooth portion 9 a. The influence of the disturbance of themagnetic flux can be removed and the rotation speed can be accuratelysensed by sensing the rotation speed at the interval of 50° CA duringthe learning of the deviation amounts of the injection characteristicsamong the cylinders. Thus, the influence due to the existence of thetoothless portion 9 b can be removed, and the rotation speed can besensed appropriately. However, it is desirable to minimize the samplinginterval of the rotation speed from the viewpoint of maintaining highaccuracy of the learning of the deviation amounts of the injectioncharacteristics among the cylinders shown in FIG. 6. If the rotationspeed is sampled at the interval of 50° CA, the interval decided by thetooth portions 9 a cannot be fully utilized although the tooth portions9 a are formed on the rotor 9 at the interval of 10° CA.

Therefore, the system according to the present embodiment performsprocessing for estimating the times necessary for the rotation of theunit angles in the angular range of 50° CA including the toothlessportion 9 b. Next, the processing will be explained in detail. Theprocessing steps of the estimation according to the present embodimentare shown in FIG. 8. The ECU 30 repeatedly performs the processing, forexample, in a predetermined cycle.

In a series of the processing shown in FIG. 8, first, Step S40 senses aunit necessary time etnint[i] as a time necessary for rotation of eachunit angle in a certain range of 50° CA, which is distant from (i.e.,opposite to) the angular range of 50° CA including the toothless portion9 a by 180° CA. Part (a) of FIG. 9 shows the waveform-shaped pulse inthe certain range, and Part (b) of FIG. 9 shows the unit necessary timesetnint[14]-etnint[18]. Step S42 of FIG. 8 calculates an average valueet50ave of the unit necessary times etnint[14]-etnint[18] by followingExpression (7). Part (b) of FIG. 9 also shows the average value et50ave.et50ave={etnint[14]+etnint[15]+etnint[16]+etnint[17]+etnint[18]}/5  Expression(7):

Step S44 of FIG. 8 calculate ratios erto[14]-erto[18] of the unitnecessary times etnint[14]-etnint[18] to the average value et50ave asshown by following Expression (8).erto[14]=etnint[14]/et50ave,erto[15]=etnint[15]/et50ave,erto[16]=etnint[16]/et50ave,erto[17]=etnint[17]/et50ave,erto[18]=etnint[18]/et50ave  Expression (8):

Following Step S46 calculates an average value et50ave2 of the timenecessary for the rotation of the angular range of 50° CA including thetoothless portion 9 b per 10° CA. Part (c) of FIG. 9 shows thewaveform-shaped pulse in the angular range. As shown in Part (d) of FIG.9, the average value et50ave2 is calculated by using the necessary timeetnint[32] between the rising edges of the waveform-shaped pulse at thethirty-second tooth portion 9 a and the toothless portion 9 b, thenecessary time etnint[33] between the rising edges of thewaveform-shaped pulse at the toothless portion 9 b, and the necessarytime etnint(0) between the rising edges of the waveform-shaped pulse atthe toothless portion 9 b and the first tooth portion 9 a. The summationof the necessary times etnint[32], etnint[33], etnint[0] accuratelyrepresents the time necessary for the rotation of the angular range of50° CA including the toothless portion 9 b. Accordingly, the averagevalue et50ave2 of the above-described angular range is calculated byusing this summation. The average value et50ave2 is calculated byfollowing Expression (9).et50ave2={etnint[32]+etnint[33]+etnint[0]}/5  Expression (9):

Following Step S48 estimates times etwrtn[32]-etwrtn[0] necessary forthe rotation of respective unit angles of 10° CA in the angular range of50° CA including the toothless portion 9 b. The timesetwrtn[32]-etwrtn[0] are estimated by multiplying the average valueet50ave2 by the ratios erto[14]-erto[18] respectively. The timesetwrtn[32]-etwrtn[0] are calculated by following Expression (10).etwrtn[32]=et50ave2×erto[14],etwrtn[33]=et50ave2×erto[15],etwrtn[34]=et50ave2×erto[16],etwrtn[35]=et50ave2×erto[17],etwrtn[0]=et50ave2×erto[18]  Expression (10):

The times etwrtn[32]-etwrtn[0] are provided by extending or shorteningthe unit necessary times etnint[14]-etnint[18] by the ratio of theaverage value et50ave2 to the average value et50ave. When the ratio isone, same magnification conversion is performed. That is, the unitnecessary times etnint[14]-etnint[18] are multiplied by the ratio of thetime necessary for the rotation of the angular range of 50° CA includingthe toothless portion 9 b to the time necessary for the rotation of theangular range between the fourteenth tooth portion 9 a and thenineteenth tooth portion 9 a.

In the present embodiment, the unit necessary timesetnint[14]-etnint[18] are used as parameters correlated with a rotationfluctuation tendency in the angular range of 50° CA including thetoothless portion 9 b. This correlation is specifically strong becausethe relationship between the angular range between the fourteenth toothportion 9 a and nineteenth tooth portion 9 a and the operation step ofthe first cylinder #1 coincides with the relationship between theangular range of 50° CA including the toothless portion 9 b and theoperation step of the fourth cylinder #4. Accordingly, the relationshipbetween the angular range between the fourteenth tooth portion 9 a andthe nineteenth tooth portion 9 a and the operation steps of all thecylinders #1-#4 coincides with the relationship between the angularrange of 50° CA including the toothless portion 9 b and the operationsteps of all the cylinders #1-#4 except for the cylinder numbers. Forthis reason, the correlation can be set at one if it is assumed that thecyclic rotation fluctuation tendency exists as shown in FIG. 3A.

However, if the time necessary for the rotation of the angular rangebetween the fourteenth tooth portion 9 a and the nineteenth toothportion 9 a differs from the time necessary for the rotation of theangular range of 50° CA including the toothless portion 9 b, absolutevalues of the rotation fluctuation differ. Therefore, the unit necessarytimes etnint[14]-etnint[18] are converted into equivalents of timesnecessary for the rotation of the unit angles in the angular range of50° CA including the toothless portion 9 b based on the differencebetween the time necessary for the rotation of the angular range betweenthe fourteenth tooth portion 9 a and the nineteenth tooth portion 9 aand the time necessary for the rotation of the angular range of 50° CAincluding the toothless portion 9 b.

The rotation speed per 10° CA can be used in the processing shown inFIG. 6 by estimating the times necessary for the rotation of the unitangles in the angular range of 50° CA including the toothless portion 9b through a series of the processing shown in FIG. 8. Accordingly, thedeviation amounts of the injection characteristics among the cylinderscan be learned with high accuracy. The NE pulse used in the processingshown in FIG. 8 is constituted by both of the waveform-shaped pulse andthe pulse that has the interval of 10° CA and that is estimated by theprocessing shown in FIG. 8.

The present embodiment exerts following effects.

(1) The unit necessary times etnint[14]-etnint[18] are converted intothe equivalents of the times necessary for the rotation of the unitangles in the angular range of 50° CA including the toothless portion 9b based on the difference between the time necessary for the rotation ofthe angular range between the fourteenth tooth portion 9 a and thenineteenth tooth portion 9 a and the time necessary for the rotation ofthe angular range of 50° CA including the toothless portion 9 b. Thus,the times etwrtn[32]-etwrtn[0] necessary for the rotation of the unitangles in the angular range of 50° CA including the toothless portion 9b can be estimated.

(2) The times etwrtn[32]-etwrtn[0] are calculated by extending orshortening the unit necessary times etnint[14]-etnint[18] by the ratioof the time necessary for the rotation of the angular range of 50° CAincluding the toothless portion 9 b to the time necessary for therotation of the angular range between the fourteenth tooth portion 9 aand the nineteenth tooth portion 9 a. Thus, the sum total of the timesetwrtn[32]-etwrtn[0] can be conformed to the sensed value of the timenecessary for the rotation of the angular range of 50° CA including thetoothless portion 9 b.

(3) The times etwrtn[32]-etwrtn[0] are estimated by multiplying theaverage value et50ave2 by the ratios erto[14]-erto[18] respectively.Thus, the values provided by extending or shortening the unit necessarytimes etnint[14]-etnint[18] by the ratio of the time necessary for therotation of the angular range of 50° CA including the toothless portion9 b to the time necessary for the rotation of the angular range betweenthe fourteenth tooth portion 9 a and nineteenth tooth portion 9 a can beprovided.

(4) The setting is made such that the relationship between the angularrange referred to during the estimation and the operation steps of therespective cylinders coincides with the relationship between the angularrange of 50° CA including the toothless portion 9 b and the operationsteps of the respective cylinders except for the cylinder numbers. Thus,the time necessary for the rotation of each unit angle in the angularrange of 50° CA including the toothless portion 9 b can be estimatedwith high accuracy.

(5) The angular range referred to during the estimation is the rangedistant from the angular range of 50° CA including the toothless portion9 b by 180° CA. Thus, the relationship between the angular rangereferred to during the estimation and the operation steps of therespective cylinders can be conformed to the relationship between theangular range of 50° CA including the toothless portion 9 b and theoperation steps of the respective cylinders except for the cylindernumbers.

(6) The instantaneous torque equivalents are calculated by carrying outthe filtering of the sensed values of the rotation speed of thecrankshaft 8 of the engine at a single frequency set based on thecombustion frequency of the engine. The injection characteristics of theinjector 16 of the engine are learned based on the instantaneous torqueequivalents calculated by the filtering. It is preferable to sample thesensed values of the rotation speed at the minimum angular interval inorder to perform the learning with high accuracy. In the presentembodiment, the rotation speed can be sampled at each unit angle decidedby the tooth portions 9 a by estimating the time necessary for therotation of the unit angle in the range including the toothless portion9 b.

Next, a system according to a second embodiment of the present inventionwill be explained in reference to drawings. In the present embodiment,if omission (temporary interruption) of the processing related to thesensing of the time necessary for the rotation of each 10° CA betweenthe tooth portions 9 a occurs due to some causes, the time necessary forthe rotation of the range, in which the omission of the processingrelated to the sensing occurs, is estimated. The processing steps of theestimation are shown in FIG. 10. The ECU 30 performs the processingshown in FIG. 10 repeatedly, for example, in a predetermined cycle.

In a series of the processing, first, Step S50 determines whether thereis omission of the processing of sensing the time necessary for therotation of each 10 ° CA between the tooth portions 9 a. The omission ofthe processing can be caused when the computation load of the ECU 30becomes excessive temporarily or can be caused by an influence of anoise, for example. If it is determined that there is omission of theprocessing related to the sensing, Steps S52-S60 perform the processingsimilar to that of Steps S40-S48 shown in FIG. 8. The processing ofSteps S52-S60 can be performed by replacing the range including thetoothless portion according to the first embodiment with a range, inwhich the processing omission occurs, in the processing of StepsS40-S48. The series of the processing is once ended if Step S50 is NO orif the processing of Step S60 is completed.

A mode of the estimation performed by this processing about the timenecessary for the rotation of each unit angle in the sensing processingomission range is shown in FIG. 11. If the sensing processing omissionoccurs in the angular range of 30° CA from the twenty-fourth toothportion 9 a to the twenty-seventh tooth portion 9 a as shown in Part (d)of FIG. 11, the estimation about the range, in which the sensingprocessing omission occurs, is performed by using this angular range andthe range of 30° CA distant from the sensing processing omission rangeby 180° CA. That is, Step S52 of FIG. 10 calculates each of unitnecessary times etnint[6]-etnint[8] necessary for the rotation of theunit angles in the angular range distant from the sensing processingomission range by 180° CA. Then, Step S54 calculates an average valueetave of the unit necessary times etnint[6]-etnint[8] by followingExpression (11).etave={etnint[6]+etnint[7]+etnint[8]}/3  Expression (11):

Then, Step S56 of FIG. 10 calculates ratios erto[6]-erto[8] of the unitnecessary times etnint[6]-etnint[8] to the average value etave. Theratios erto[6]-erto[8] are defined by following Expression (12).erto[6]=etnint[6]/etave,erto[7]=etnint[7]/etave,erto[8]=etnint[8]/etave  Expression (12):

Then, Step S58 of FIG. 10 calculates an average value etave2 of the timenecessary for the rotation of the angular range, in which the sensingprocessing omission occurs, per 10° CA. The average value etave2 iscalculated by following Expression (13) using the time t1 of the risingedge of the twenty-fourth waveform-shaped pulse and the time t2 of therising edge of the twenty-seventh waveform-shaped pulse.etave2=(t2−t1)/3  Expression (13):

Then, Step S60 of FIG. 10 estimates times etwrtn[24]-etwrtn[26]necessary for rotation of unit angles of the angular range, in which thesensing processing omission occurs, based on following Expression (14).etwrtn[24]=etave2×erto[6],etwrtn[25]=etave2×erto[7],etwrtn[26]=etave2×erto[8]  Expression (14):

Thus, the times necessary for the rotation of the unit angles of theangular range, in which the sensing processing omission occurs, can beestimated appropriately.

The present embodiment exerts effects similar to the effects (1)-(6) ofthe first embodiment about the range, in which the sensing processingomission occurs.

In the present embodiment, the unit necessary time etnint[24] can besensed at 360° CA before the sensing processing omission occurs. Thetime etwrtn[24] can be estimated by multiplying the previous ratio ofthe unit necessary time etnint[23] to the unit necessary time etnint[24] by the present unit necessary time etnint[23] through the methoddescribed in JP-A-2005-48644. However, with this method, the estimationaccuracy of the time etwrtn[24] deteriorates compared to the methodaccording to the present embodiment. That is, for example, in the casewhere an angular error occurs such that the position where thetwenty-fourth tooth portion 9 a is deviated toward the twenty-fifthtooth position 9 a, the interval between the twenty-third tooth portion9 a and the twenty-fourth tooth portion 9 a is long and the intervalbetween the twenty-fourth tooth portion 9 a and the twenty-fifth toothportion 9 a is short. Accordingly, a large error is caused in theprevious ratio of the unit necessary time etnint[23] to the unitnecessary time etnint[24].

In contrast, with the method according to the present embodiment, theinfluence because of the above-described angular error as of theestimation is alleviated compared to the method of JP-A-2005-48644 evenif the angular error occurs in the sixth tooth portion 9 a. Moreover,with the method of JP-A-2005-48644, in order to perform the estimation,the above-described ratio has to be beforehand calculated before thesensing processing omission occurs. In contrast, with the methodaccording to the present embodiment, the estimation can be performedeven after the sensing processing omission occurs.

The above-described embodiments may be modified and implemented asfollows, for example.

In the above-described embodiments, the time necessary for the rotationof each unit angle in the angular range requiring the estimation isestimated based on the time necessary for the rotation of the unit anglein the angular range distant from the requiring angular range by 180°CA. In the case of a five-cylinder diesel engine, it is preferable toset a distance of 144° CA therebetween such that the relationshipbetween the angular range requiring the estimation and the operationsteps of all the cylinders of the engine coincides with the relationshipbetween the angular range used for the above-described estimation andthe operation steps of all the cylinders except for the cylindernumbers.

In the example of the above-described four-cylinder engine, the angularrange preceding by 540° CA may be used. The estimation accuracy isimproved more as the angular range requiring the estimation and theangular range used for the estimation are closer to each other.Therefore, generally, in the engine that causes the combustion strokesat equal crank angle intervals, the angular range requiring theestimation and the angular range used for the estimation should bepreferably distanced by 720/n° CA (n: number of cylinders). Thus, therelationship between the angular range requiring the estimation and theoperation steps of all the cylinders can be conformed to therelationship between the angular range used for the above-describedestimation and the operation steps of all the cylinders except for thecylinder numbers. At the same time, the angular range requiring theestimation and the angular range used for the estimation can be broughtas close to each other as possible.

In the above-described embodiments, the ratio of the time (unitnecessary time) necessary for the rotation per unit angle to the averagevalue of the time (second necessary time) necessary for the rotation ofthe unit angle of the angular range used for the estimation ismultiplied by the average value of the time necessary for the rotationof the angular range requiring the estimation per unit angle.Alternatively, for example, a ratio of the time (first necessary time)necessary for the rotation of the requiring angular range to the secondnecessary time may be multiplied by the unit necessary time to calculatethe estimated value. Alternatively, differences between the unitnecessary times and the average value of the unit necessary times may bemultiplied by the ratios of the first necessary time to the secondnecessary time, and the summations of the multiplied values and theaverage value of the first necessary time per unit angle may be used asthe estimated values. Alternatively, the difference between the firstnecessary time and the second necessary time may be converted into thedifference per unit angle and the difference may be added as an offsetamount to the unit necessary times to calculate the estimated values.

The usage of the estimated values of the times necessary for therotation of the unit angles in the angular range is not limited to thelearning of the deviation amounts of the fuel injection characteristicsas illustrated in FIG. 6. For example, misfire detection can also beperformed with high accuracy by using the above-described estimatedvalues.

The internal combustion engine is not limited to the diesel engine butmay be a gasoline engine.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A controller of an internal combustion engine having a function ofsensing times necessary for rotation of unit angles of a crankshaft ofthe engine based on an output of a crank angle sensor that senses sensedportions provided at equal intervals of the unit angles on a rotatingbody rotating in synchronization with rotation of the crankshaft,wherein the rotating body has a reference portion formed between thesensed portions by irregularly changing the regular arrangement of thesensed portions, the controller comprising: a first necessary timesensing device that senses a first necessary time necessary for rotationof an arbitrary angular range of the crankshaft wherein the arbitraryangular range includes the reference portion and has a larger angle thanthe unit angle; a second necessary time sensing device that senses asecond necessary time necessary for rotation of an another angular rangethat is different from the arbitrary angular range and that has the sameangle as the arbitrary angular range, wherein the sensed portions areprovided throughout the another angular range at the equal intervals ofthe unit angles; a unit necessary time sensing device that senses aplurality of unit necessary times which are respectively necessary forrotation of the respective unit angles in the another angular rangedifferent from the arbitrary angular range; and an estimating devicethat estimates time necessary for rotation of each unit angle in thearbitrary angular range by converting the unit necessary time into anequivalent of the time necessary for the rotation of the unit angles inthe arbitrary angular range based on a difference between the firstnecessary time and the second necessary time.
 2. The controller as inclaim 1, wherein the estimating device employs values provided byextending or shortening the unit necessary times by a ratio of the firstnecessary time to the second necessary time as the estimated values ofthe times necessary for the rotation of the unit angles in the arbitraryangular range.
 3. The controller as in claim 1, wherein the engine is amulti-cylinder internal combustion engine, and the controller is setsuch that a relationship between the different angular range and anoperation step of a certain cylinder coincides with a relationshipbetween the arbitrary angular range and the operation step of thecertain cylinder or an operation step of a different cylinder.
 4. Thecontroller as in claim 1, wherein the different angular range is distantfrom the arbitrary angular range by a crank angle provided by dividing720°CA by an integer value.
 5. The controller as in claim 1, wherein thearbitrary angular range includes the reference portion and a pair ofsensed portions adjacent to the reference portion.
 6. The controller asin claim 1, further comprising: a rotation time sensing device thatsuccessively senses the times necessary for the rotation of the unitangles of the crankshaft; and a monitoring device that monitorsoccurrence of interruption of the sensing processing performed by therotation time sensing device, wherein when the monitoring device detectsthe interruption, the controller employs an angular range, in which theinterruption occurs, as the arbitrary angular range.
 7. The controlleras in claim 1, wherein the sensed portions comprise tooth portions ofthe rotating body and the reference portion comprise a toothless portionof the rotating body.
 8. A controller of an internal combustion enginehaving a function of sensing times necessary for rotation of unit anglesof a crankshaft of the engine based on an output of a crank angle sensorthat senses sensed portions provided at equal intervals of the unitangles on a rotating body rotating in synchronization with rotation ofthe crankshaft, the controller comprising: a first necessary timesensing device that senses a first necessary time necessary for rotationof an arbitrary angular range of the crankshaft; a second necessary timesensing device that senses a second necessary time necessary forrotation of an angular range different from the arbitrary angular range;a unit necessary time sensing device that senses a plurality of unitnecessary times necessary for rotation of the unit angles in the angularrange different from the arbitrary angular range; and an estimatingdevice that estimates times necessary for rotation of the unit angles inthe arbitrary angular range by convening the unit necessary times intoequivalents of the times necessary for the rotation of the unit anglesin the arbitrary angular range based on a difference between the firstnecessary time and the second necessary time; wherein: the estimatingdevice employs values provided by extending or shortening the unitnecessary times by a ratio of the first necessary time to the secondnecessary time as the estimated values of the times necessary for therotation of the unit angles in the arbitrary angular range; and theestimating device includes: an average value calculating device thatcalculates an average value of the first necessary time per unit angle;a ratio calculating device that calculates ratios of the unit necessarytimes to an average value of the second necessary time per unit angle;and an employing device that employs products of the average value ofthe first necessary time per unit angle and the ratios as the estimatedvalues of the times necessary for the rotation of the unit angles in thearbitrary angular range.
 9. A controller of an internal combustionengine having a function of sensing times necessary for rotation of unitangles of a crankshaft of the engine based on an output of a crank anglesensor that senses sensed portions provided at equal intervals of theunit angles on a rotating body rotating in synchronization with rotationof the crankshaft, the controller comprising: a first necessary timesensing device that senses a first necessary time necessary for rotationof an arbitrary angular range of the crankshaft; a second necessary timesensing device that senses a second necessary time necessary forrotation of an angular range different from the arbitrary angular range;a unit necessary time sensing device that senses a plurality of unitnecessary times necessary for rotation of the unit angles in the angularrange different from the arbitrary angular range; an estimating devicethat estimates times necessary for rotation of the unit angles in thearbitrary angular range by converting the unit necessary times intoequivalents of the times necessary for the rotation of the unit anglesin the arbitrary angular range based on a difference between the firstnecessary time and the second necessary time; a filtering device thatcalculates an instantaneous torque equivalent by filtering a sensedvalue of rotation speed of the crankshaft at a single frequency setbased on a combustion frequency of the engine; and a learning devicethat learns injection characteristics of an injector of the engine basedon the instantaneous torque equivalent calculated by the filteringdevice, wherein the filtering device uses the rotation speed calculatedbased on the times estimated by the estimating device.
 10. A controllerof an internal combustion engine having a function of sensing timesnecessary for rotation of unit angles of a crankshaft of the enginebased on an output of a crank angle sensor that senses sensed portionsprovided at equal intervals of the unit angles on a rotating bodyrotating in synchronization with rotation of the crankshaft and areference portion formed between the sensed portions by irregularlychanging the regular arrangement of the sensed portions, the controllercomprising: a first necessary time sensing device that senses a firstnecessary time necessary for rotation of a first angular range includingthe reference portion and a pair of sensed portions adjacent to thereference portion; a second necessary time sensing device that senses asecond necessary time necessary for rotation of a second angular rangethat is different from the first angular range and that has the sameangle as the first angular range; a unit time sensing device that sensesa plurality of unit necessary times, which are respectively necessaryfor rotation of the respective unit angles in the second angular range;and an estimating device that estimates time necessary for rotation ofeach unit angle in the first angular range by converting the unitnecessary time into an equivalent of the time necessary for the rotationof the unit angle in the first angular range based on a differencebetween the first necessary time and the second necessary time.
 11. Thecontroller as in claim 10, wherein the sensed portions comprise toothportions of the rotating body and the reference portion comprise atoothless portion of the rotating body.
 12. A controller of an internalcombustion engine having a function of sensing times necessary forrotation of unit angles of a crankshaft of the engine based on an outputof a crank angle sensor that senses sensed portions provided at equalintervals of the unit angles on a rotating body rotating insynchronization with rotation of the crankshaft, the controllercomprising: a rotation time sensing device that successively senses thetimes necessary for the rotation of the unit angles of the crankshaft; amonitoring device that monitors occurrence of interruption of thesensing processing performed by the rotation time sensing device; and afirst estimating device that estimates times necessary for rotation ofunit angles in a certain angular range, in which the interruption occursand which has a larger angle than the unit angle, when the monitoringdevice detects the interruption, wherein the first estimating deviceincludes: a first necessary time sensing device that senses a firstnecessary time necessary for rotation of the certain angular range; asecond necessary time sensing device that senses a second necessary timenecessary for rotation of another angular range that is different fromthe certain angular range and that has the same angle as the certainangular range; a unit time sensing device that senses a plurality ofunit necessary times, which are respectively necessary for rotation ofthe respective unit angles in the another angular range; and a secondestimating device that estimates time necessary for rotation of eachunit angle in the certain angular range by converting the unit necessarytime into an equivalent of the time necessary for the rotation of theunit angle in the certain angular range where the based on a differencebetween the first necessary time and the second necessary time.
 13. Thecontroller as in claim 12, wherein the sensed portions comprise toothportions of the rotating body, the rotating body further includes atoothless portion.